Buggies Gone Wild Golf Cart Forum - View Single Post - why not 3-12's for 36 volt lithium?

Pat911 · 08-10-2022, 04:51 PM

Lithium batteries are protected by a Battery Management System, or BMS. With 3 12v batteries you’ll have 3 BMS’s doing their own thing and not knowing about the other two. With a 36v battery, there’s only one BMS protecting the whole pack.

I’ve written about this extensively in the past but simply, when charging, if one battery becomes fully charged the BMS will disconnect, protecting it from overcharging, but when this happens, the other two batteries will also stop charging. Over time you’ll end up with three batteries that are vastly out of balance and your 100Ah pack, for example, may be reduced to only a 50Ah or 70Ah pack.

Secondly, most general purpose 12v lithium batteries cannot produce the required current to power a cart, especially if it’s modified in any way.

Specific to you John, adding a fourth battery at a later stage will only exasperate the imbalance problem described above as the fourth battery will be at least one of the following, different batch, different capacity, different age, different internally even though it’s the same battery externally etc.

Go for a single 36v battery and you’ll never look back, or go for 48v and do the upgrade now.

Cheers
Pat.

08-10-2022, 04:51 PM	#3
Pat911 Gone Wild Join Date: Dec 2020 Location: Melbourne, Australia Posts: 1,941	Re: why not 3-12's for 36 volt lithium? Lithium batteries are protected by a Battery Management System, or BMS. With 3 12v batteries you’ll have 3 BMS’s doing their own thing and not knowing about the other two. With a 36v battery, there’s only one BMS protecting the whole pack. I’ve written about this extensively in the past but simply, when charging, if one battery becomes fully charged the BMS will disconnect, protecting it from overcharging, but when this happens, the other two batteries will also stop charging. Over time you’ll end up with three batteries that are vastly out of balance and your 100Ah pack, for example, may be reduced to only a 50Ah or 70Ah pack. Secondly, most general purpose 12v lithium batteries cannot produce the required current to power a cart, especially if it’s modified in any way. Specific to you John, adding a fourth battery at a later stage will only exasperate the imbalance problem described above as the fourth battery will be at least one of the following, different batch, different capacity, different age, different internally even though it’s the same battery externally etc. Go for a single 36v battery and you’ll never look back, or go for 48v and do the upgrade now. Cheers Pat.